Indoor positioning services refers to methods where networks of devices and algorithms are used to locate mobile devices within buildings. Indoor positioning is regarded as a key component of location-aware mobile computing and is an important element in provided augmented reality (AR) services. Location aware computing refers to applications that utilize a user's location to provide content relevant to location. Additionally, AR is a technology that overlays a virtual space onto a real (physical) space. To successfully enable AR and location aware computing, accurate indoor positioning is an important requirement.
Global Positioning Systems (GPS) loses significant power when passing through construction materials, and suffers from multi-path propagation effects that make it unsuitable for indoor environments. Techniques based on received signal strength indication (RSSI) from WiFi and Bluetooth wireless access points have also been explored. However, complex indoor environments cause radio waves propagate in dynamic and unpredictable ways, limiting the accuracy of positioning systems based on RSSI. Ultrasonic techniques (US), which transmit acoustic waves to microphones, are another method which can be used to approximate indoor position. They operate at lower frequencies than systems based on WiFi and attenuate significantly when passing through walls. This potentially makes US techniques more accurate than WiFi or Bluetooth techniques.
Optical indoor positioning techniques use optical signals, either visible or infrared, and can be used to accurately locate mobile devices indoors. These are more accurate than the approaches mentioned previously, since optical signals are highly directional and cannot penetrate solid objects. However this directionality limits the potential reliability of optical signals, since difficulty in aligning the receiver and transmitter can occur.
A variety of systems transmit a one-way authentication signal from an infrastructure endpoint to a mobile device. Applications that make use of one-way authentication include mobile loyalty solutions, ticketing, secure access control, payments, media sharing, and social media. A common technology used for one-way authentication is Quick Response Codes (“QR codes”). QR codes are two-dimensional barcodes. Mobile devices that include cameras can take a picture of the QR code and then decode the information associated with the QR code. However, QR codes have the disadvantage of being easily copied. Anyone having a device with a camera can take a picture of a QR code, print it out, and replicate it. For example, when QR codes are used in mobile loyalty solutions, it is possible for users to cheat the system by taking pictures of the QR codes and submitting fake scans. An alternative emerging technology is Near-Field-Communication (NFC), which uses radio frequency transmission to transmit an authentication message over a short distance. However, NFC is still in the nascent stages of adoption. Many mobile devices do not have NFC capabilities, and NFC terminals have not yet been widely deployed.